Process for developing photosensitized anodized aluminum plates



United States Patent 3,275,440 PROCESS FOR DEVELOPING PHOTOSENSITIZED ANODIZED ALUMINUM PLATES Robert A. Kempe, Hudson, and Kazimierz R. Szczepaniak, Cleveland, Ohio, assignors to Metalphoto Corporation, Cleveland, Ohio No Drawing. Filed Aug. 12, 1963, Ser. No. 301,606 4 Claims. (CI. 96-66) This invention relates to the developing of images produced as the result of photographic exposure of photosensitized anodized aluminum plates. More particularly, it relates to developer compositions w-hich yield a high contrast image at relatively high speeds and to their use in obtaining images of the type indicated.

Photosensitized anodized aluminum plates are described in the United States Patent 2,995,443, issued to Robert A. Kempe on August 8, 1961, and in United States Patents 2,115,339, 2,126,017 and 2,766,119 mentioned therein, as well as in other literature of this art. In general it is preferred to follow the techniques described in the prior patents for the preparatory portion of the present process. This comprises careful cleaning of an aluminum sheet followed by anodizing of the clean sheet under such conditions that a suitable layer of aluminum oxide is formed on the surface, a suitable layer being one which is durable, porous and transparent. After the aluminum plates have been provided with a durable porous film of aluminum oxide they are ready for photosensitization, e.g., by soaking in a photosensitive mixture as described in any of the above noted patents. Thereafter the sensitized plate is stored in the usual way, in a dark cool place until it is to be exposed, or it may be used as soon as it is prepared, if desired.

Imagewise exposure may be effected in any convenient way, usually by use of a negative image between a light source and the sensitized plate. Thereafter the image is developed and it is to this stage of the process that the present invention pertains.

Briefly, it has been found that to produce a high contrast image, standard photograph developers which are satisfactory when developing images on paper bases are not entirely suitable when developing images on anodized aluminum, for reasons which are not fully understood.

One object of the invention is to produce high contrast and low fog in images developed in anodized alu- Another object of the invention is to produce high contrast and low fog in images developed in anodized aluminum and in short developing time.

Still another object of the invention is to eliminate prewetting of anodized aluminum plates before development.

A further object of the invention is to eliminate sponging of the anodized aluminum plates after development.

An important object of this invention is to provide a long-working, high-speed, high-contrast, low-fog developer for developing images in anodized aluminum layers.

Another object of this invention is to provide nonstaining developer for anodized aluminum materials.

Another object of this invention is to provide a developer for anodized aluminum plates with a broad working temperature range.

Another object of this invention is to provide a developer for anodized aluminum plates which can be used for line as well as half-tone work.

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These-and other objects are achieved by using a developer having compositions within the following relative proportions:

Sufiicient Water should be-used with the above-constituents to makeat least 1 liter, although more dilute solutions may also be used.

In the foregoing formula, metol which is a monomethyl para-amino-phenol-sulphate and is also known as l-hydroxy, 4-methyl amino benzene sulfate can be replaced by similar compounds such as 2,4-diamino phenyl hydrochloride which is also known as amidol.

Similarly, instead of hydroquinone, chloroquinol or phenidone or other known equivalents may be used in the developer of this invention.

Furthermore the lower alcohol may be either isopropanol (preferred) or ethanol or methanol. in the formula, it is an optional ingredient and may be omitted.

Any anionic surface active agent or wetting agent may be used, Tergitol-Anionic 08 and Aerosol O.T. a sodium sulfosuccinate being particularly preferred.

-A solution of benzotriazole (6-19 g./l.) has been found to give 'better results in the composition shown, than any other inhibitors tested and is preferred. The results obtained with other fog inhibitors such as alkali metal halides e.g. KI or KBr or other compounds which form silver salts having solubilities approaching the solubility of A-gCl have been found to give noticeably inferior results.

Using the foregoing developer, the developing time is substantially shorter than has been heretofore considered possible, and is from 2.5 to '3 minutes when using freshly prepared developer at room temperature or only 1.5 to 2 minutes when the developer is used at to F.

With the developer composition described above no noticeable fog was observed even after developing images on sensitized anodized aluminum plates for intervals as long as 10-15 minutes. In contrast with previously used metol-hydroquinone developers it is not necessary to immerse the entire plate at one time, or to pre-wet the plate prior to immersion when using the developer of the present invention.

Finally it has been found that the developer of the above composition may be used for much longer service than those previously employed.

After developing for 3 /2 minutes at -68-70'F. e.g. in the preferred composition given above by way of illustration, the image is fixed in a conventional hypo solution in the usual way and a more pleasing contrast may be obtained by immersing the plate in a commercial gold chloride toner, or similar bath.

Having now described the invention in accordance with the patent statutes it is not intended that it be limited except as required by the appended claims.

We claim:

1. In the manufacture of an aluminum photographic plate in a method which includes anodizing the surface of a clean aluminum plate to provide a porous, durable and transparent layer of aluminum oxide thereon, and.

thereafter impregnating said porous oxide layer with a photosensitive composition and then imagewise exposing the resulting photosensitive article, the improvement which comprises developing a visible image on the exposed photosensitized plate by immersing the same in a developer solution having a composition consisting essentially of:

and suflicient water to make 1 liter of solution and after removing the plate from the developer, fixing the image. 2. The process of claim 1 in-which the 'fog inhibitor is benzotriazolc.

'3. The process of claim 1 wherein the developer solution has a composition consisting essentially of:

Metol v.. grams 3 Sodium sulfite, desiccated do 40 Hydroquinone do 6.5

Alkali metal carbonate, monohydrate do 30 Lower alcohol ml Anionic wetting agent -ml 0.4 r

Fog inhibitor l 3 dissolved in suflicient water to make up one liter of solution.

4. The process of claim 3, wherein the fog inhibitor is benzotriazole.

References Cited by the Examiner UNITED STATES PATENTS 2,541,470 2/ 1 1 Henn et a1 96-66 2,940,851 6/1960 Beavers et al. 9,666 3,005,710 10/ 1961 Levy 96- 66 X OTHER REFERENCES Mees, C. E. K., The Theory of the Photographic Process, New York, The MacmillanCompany, 1954, pages 677-680.

Photo Dictionary and Quick Reference Guide, New York, Morgan & Morgan, 'Inc., 1957, pages 79-80.

NORMAN C. TORCIHIIN, Primary Examiner.

J. TRAVIS BROWN, Examiner.

C. E, DAVIS, Assistant Examiner. 

1. IN THE MANUFACTURE OF AN ALUMINUM PHOTOGRAPHIC PLATE IN A METHOD WHICH INCLUDES ANODIZING THE SURFACE OF A CLEAN ALUMINUM PLATE TO PROVIDE A POROUS, DURABLE AND TRANSPARENT LAYER OF ALUMINUM OXIDE THEREON, AND THEREAFTER IMPREGNATING SAID POROUS OXIDE LAYER WITH A PHOTOSENSITIVE COMPOSITION AND THEN IMAGEWISE EXPOSING THE RESULTING PHOTOSENSITIVE ARTICLE, THE IMPROVEMENT WHICH COMPRISES DEVELOPING A VISIBLE IMAGE ON THE EXPOSED PHOTOSENSITIZED PLATE BY IMMERSING THE SAME IN A DEVELOPER SOLUTION HAVING A COMPOSITION CONSISTING ESSENTIALLY OF: 